The plantar fascia is a fibrous tissue that spans between the medial tubercle of the calcaneus (or heel bone) to the metatarsals (or toe bones). When a person stands, the plantar fascia is stretched under the load of the person's weight. This is known as the “bowstring effect.” Should the toes and ankle be dorsiflexed (or hyperextended upward toward the shin) the plantar fascia is stretched even further. This is called the “windlass effect.”
Plantar fasciitis is a condition that occurs to a wide range of the adult population. It is seen in both sedentary and active individuals. The cause of plantar fasciitis is unclear; however, a common theory is that the plantar fascia is repetitively injured causing partial tears and chronic inflammation. As these micro tears heal, scar tissue forms reducing the elasticity of the plantar fascia and contributing to further tearing and inflammation.
Prolonged standing, obesity, pronation of the foot while walking, running, jumping and other activities can cause repeated injuries to the origin of the plantar fascia at its insertion on the medial tubercle of the calcaneus of the foot. The injuries result in the repetitive tearing of tissue, inflammation, and the formation of scar tissue in the plantar fascia causing limitation in flexibility. The injury causes intense pain in the bottom of the foot near the heel. When suffering from injury to the plantar fascia, one incurs the greatest pain in the morning when arising from bed because the plantar fascia has not been exercised during the night and has become stiff and retracted as a result of the long period of inactivity. When one rises from bed and first applies full body weight to his or her feet, the plantar fascia is suddenly stretched resulting in sharp pains to the heel. Studies have shown it is desirable to gradually exercise the plantar fascia by dorsiflexing the toes and ankles, stretching it gradually, especially before one first applies one's body weight to his or her feet.
Some doctors advise their patients who suffer from such injuries to roll a towel and grasp the ends in each hand and press the toes of the injured foot against the center of the towel while using one's arms to pull against the towel to thereby stretch the plantar fascia. The exercise is marginally successful because the patient must stiffen his toes to grip the towel and prevent it from sliding off the end of this foot. The exercise, therefore, requires the flexing of the plantar fascia, and the plantar fascia is not stretched as is needed.
Several devices have been proposed for stretching the plantar fascia, but such devices suffer from some of the same limitations incurred with the towel namely, the device will not stay affixed to the foot in such a manner as to permit the foot to relax and thereby maximize the stretching of the plantar fascia.
Other devices require weight bearing stretching that provide a stretch to the plantar fascia only after the additional micro tears have occurred from the individual standing. Still other devices offer passive stretching of the plantar fascia. These devices require that sufferer to wear bulky splints while they sleep. Patient compliance is low due to the uncomfortable feeling inherent with these devices.